Novel Flp pilus biogenesis-dependent natural transformation
Novel Flp pilus biogenesis-dependent natural transformation
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DOI：
10.3389/fmicb.2015.00084
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发表时间：
2015-02-10
影响因子：
5.2
通讯作者：
Liebl, Wolfgang
中科院分区：
文献类型：
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作者：
Angelov, Angel;Bergen, Paul;Liebl, Wolfgang
几乎所有主要分类群中的细菌物种都已描述了自然转化。然而，目前对结构成分和能力发展调节的理解仅来自于少数模式生物。尽管四十多年前就在放线菌（高 GC 革兰氏阳性菌）成员中发现了自然转化，但尚未在整个门的任何代表中研究其结构成分或能力系统的调节。在本报告中，我们确定了一种独特类型的菌毛生物发生基因（tad 基因，用于紧密粘附）的新作用，迄今为止，该基因仅与生物膜形成、粘附和毒力特征有关。在藤黄微球菌基因组中发现的类tad基因被证明是该放线菌物种遗传转化所必需的。我们为两个预测的 tad 基因簇的每个开放阅读框以及潜在的前菌毛蛋白加工肽酶生成并分析了单独的敲除突变体，并鉴定了假定的菌毛的主要成分。通过表达主要前毛蛋白亚基的标记变体和免疫荧光显微镜，我们观察到从细胞表面延伸的丝状结构。我们的数据表明，两个 tad 基因岛互补地有助于该生物体功能菌毛的形成。自然转化中tad基因的参与似乎不仅对藤黄微球菌来说是独一无二的，而且在放线菌的其他代表中也可能被证明是这种情况，其中包含重要的医学和生物技术相关物种。
Natural transformation has been described in bacterial species spread through nearly all major taxonomic groups. However, the current understanding of the structural components and the regulation of competence development is derived from only a few model organisms. Although natural transformation was discovered in members of the Actinobacteria (high GC Gram-positive bacteria) more than four decades ago, the structural components or the regulation of the competence system have not been studied in any representative of the entire phylum. In this report we identify a new role for a distinct type of pilus biogenesis genes (tad genes, for tight adherence), which so far have been connected only with biofilm formation, adherence and virulence traits. The tad-like genes found in the genome of Micrococcus luteus were shown to be required for genetic transformation in this actinobacterial species. We generated and analyzed individual knockout mutants for every open reading frame of the two predicted tad gene clusters as well as for a potential prepilin processing peptidase and identified the major component of the putative pili. By expressing a tagged variant of the major prepilin subunit and immunofluorescence microscopy we visualized filamentous structures extending from the cell surface. Our data indicate that the two tad gene islands complementarily contribute to the formation of a functional competence pilus in this organism. It seems likely that the involvement of tad genes in natural transformation is not unique only for M. luteus but may also prove to be the case in other representatives of the Actinobacteria, which contains important medically and biotechnologically relevant species.